A prominent Silicon Valley venture capitalist has stepped into the middle of a long-standing controversy over a California tradition: open access to the state's famed beaches.

In a lawsuit filed this week, the Surfrider Foundation, a coastal protection group, alleges that the owner of a beachfront property south of San Francisco has violated the law by closing an access road that has long been used by local surfers and fisherman to reach a spit of sand called Martin's Beach.

"It's the most beautiful beach in San Mateo County," said Mark Massara, a lawyer for Surfrider. Massara says he surfs often at the beach and believes the law provides for access to everyone.

While documents list the owner of the property as Martin's Beach LLC, a person familiar with the matter says the owner is Vinod Khosla, a co-founder of Sun Microsystems and a prominent venture capitalist known for investing in clean-energy technology.

In California, unlike in most other states, all beaches are open to the public under the constitution. But private landowners are not always required to allow access to the coastline across their property, and many disputes have arisen over the years - often involving wealthy beachfront homeowners.

In the case of the Martin's Beach property, the previous owner had long allowed locals to access the beach for a fee. But the new owner, who bought the property in 2008 and soon after installed gates on the access road and hired guards to keep people out - infuriating locals, who staged a protest at the property on Thursday.

Lawyers for Surfrider say California's Coastal Act calls for permits around activities that change the use or intensity of use at a beach - permits Martin's Beach LLC failed to acquire before installing the gates.

Khosla made his name as a co-founder of Sun Microsystems and later joined the blue-chip venture firm Kleiner Perkins Caufield & Byers. He started Khosla Ventures in 2004, and the firm known for investing in clean-technology companies such as renewable energy company KiOR and renewable-products company Amyris.

In California, unlike in most other states, all beaches are open to the public under the constitution. But private landowners are not always required to allow access to the coastline across their property, and many disputes have arisen over the years - often involving wealthy beachfront homeowners.

That's as clear as muddy water. All beaches must be open and yet private landowners are not required to allow access. Just wow. Typical government thinking.